In the regulation of cortical excitability tonus, Kupalov described a particular acquired, learned mechanism, the shortened conditional Reflex (SCR). SCR is an essential mechanism by which an adequate cortical tonus is established by environmental cues as an anticipatory set-up preparing the individual qualitatively and quantitatively for expected forthcoming events. An original physiological example is given, the conditional "transfer" of motor behavior at cortical electrical stimulation. Three psychopharmacological implications are presented, namely environmental-dependent, stress-related events, environmental-dependent drug conditioning, and drug-tolerance experiments. Future eventual psychophysiological and psychopharmacological lines of research related to the shortened conditional reflex concept are discussed.